The present invention relates to a grinding machine having a size-measuring device for intermittently measuring a size of a workpiece.
A method for controlling a cutting operation while the size of workpiece is continuously measured by an inprocess, is known. This prior art method comprises the steps of: detecting the position of a cutting table and a residual amount of cutting corresponding to a deflection of the shaft of the grinding stone on the basis of the difference of the size signal from the size-measuring device, and controlling the position of the cutting table in such a way that the residual amount of cutting is always constant.
However, in the case of grinding the interior of workpiece in size, it is alternately required for measuring the size of the workpiece to touch the workpiece with a contactor of the size-measuring device and to detach the contactor from the workpiece in relation to the reciprocating motion of the shaft of the grinding stone. Therefore, when the method for controlling the position of the cutting table is applied to the grinding machine in which the size of the workpiece is intermittently measured, the position of the cutting base is necessarily moved intermittently every measuring operation, so that a controlling error is produced in relation to the measuring interval. Consequently, it is difficult to control the residual amount of the cutting to always be constant.
The present invention is intended to improve the conventional method, and an object of the present invention is to provide a control system of a grinder which is capable of maintaining the residual amount of cutting constant by controlling the speed of a cutting table at the interval of the measuring timing so that movement of a cutting table is kept in an approximate linear condition.
The grinding machine control device of the present invention comprises a workpiece size-measuring device for intermittently measuring a size of a workpiece, a position detector for detecting the position of a cutting table; means for computing the transient residual amount of cutting in synchronization with the measuring timing on the basis of the detected size and position of the workpiece, means for computing a speed correcting component on the basis of the error in said residual amount to the reference residual amount of cutting, and a cutting control means for controlling the speed of the cutting table by adding said speed correcting component to the present speed of the cutting table. An embodiment of the present invention will now be described in more detail in conjunction with the drawings.